The Human Strategy

An Evolutionary Perspective on Human Anatomy

John H. Langdon

The Human Strategy

An Evolutionary Perspective on Human Anatomy

John H. Langdon

Description

The Human Strategy brings a unique and accessible evolutionary approach to the study of human anatomy. Bridging the disciplines of anthropology and biology, it acknowledges that human beings are vertebrates, mammals, and primates, and that the anatomical systems of the human body reflect adaptations from each of these levels of classification. John H. Langdon identifies the significance of those traits that make humans distinct from other vertebrates, exploring adaptations to the musculoskeletal, nervous, and reproductive systems and to systems of homeostasis. He addresses the question: "What functions are represented in the body structure and what history lies behind them?" Framing the answers in terms of physiological goals, functional adaptation, and evolutionary contingency, he covers both soft- and hard-tissue systems. Langdon considers how behavioral changes in our ancestors--bipedalism and a changing diet that incorporated meat--relate to anatomical changes in nearly every organ system and contributed to expansion of the brain, a higher energy budget, and a prolongation of life history. Integrating the most recent research in the field, The Human Strategy features more than 250 clear and well-labeled illustrations that explain anatomical systems and processes. It includes tables that detail the differences between the major classes of vertebrates, helping students to put evolutionary variations among species in context. A comprehensive glossary and an extensive bibliography are also provided. Ideal for upper-level undergraduate and graduate courses in human evolutionary anatomy, The Human Strategy can also be used in human anatomy and human evolution courses. Taking a more complete look at the human body in an evolutionary sense than any other existing text--and demonstrating that the human present is best understood in terms of our past--this volume serves as an excellent starting point for discussion, critical thinking, and further research.

The Human Strategy

An Evolutionary Perspective on Human Anatomy

John H. Langdon

Table of Contents

List of TablesPrefacePART I. INTRODUCTION 1. EVOLUTION AND ADAPTATION What Is Evolution? The Theory of EvolutionThe Evidence for EvolutionDarwinism: Evolution by Natural Selection Natural SelectionEvidence for Natural SelectionThe Origin of Heritable VariationHow Variation Takes FormDifferences in Degree of DevelopmentDifferences in Direction of DevelopmentThe Limits of Natural SelectionSexual SelectionAdaptationism: An Evolutionary Perspective Other Paths to AdaptationImportant Evolutionary Concepts 2. A PLACE IN NATURE: HUMANS IN AN EVOLVING WORLD A Place in Time A Place in Life: Biological Classification Comparative Background of the HumanSpecies Kingdom AnimaliaPhylum ChordataSubphylum VertebrataTetrapodsClass MammaliaOrder PrimatesFamily HominidaeThe Emergence of HumansPART II. MUSCULOSKELETAL SYSTEM 3. BONES, JOINTS, AND MUSCLES Stresses and Strains Cartilage Bone Development and Growth of BoneRemodeling of BoneAdaptations of Mammalian BoneLigament and Tendon Joints Accessory and Conjunct MotionsMuscle Concepts of Functional Design Reduction of MassEnergetic Efficiency4. THE SKULL The Human Skull Evolution of the Mammalian Skull Origins of the Vertebrate CraniumMammalian Modifications of the Tetrapod SkullChanges in the Primate Skull The Primate FaceOrbital ConvergenceShortening the FaceThe Cranial VaultBrowridgesBasicranial FlexionMechanics of Head BalanceJaws The Mandibular Symphysis and the ChinThe Australopithecine Chewing ComplexThe Problem of Skeletal and Dental Reduction 5. TEETH Tooth Development Evolution of Vertebrate Teeth Origins of TeethMammalian Dental AdaptationsThe Tribosphenic MolarHominin Teeth Dental FormulaeAnterior DentitionPosterior DentitionThe Dental Arcade and the Chewing CycleHominin Enamel AdaptationsDental Adaptations of the NeanderthalsModern Trends and Variations in Human Dentition6. THE SPINE Stages in the Evolution of Vertebrate BodyDesign FishEarly TetrapodsMammalsStructure of the Human Vertebral Column Intervertebral JointsRegions of the Human SpineCurvatures of the SpineFossil EvidenceMusculature of the Trunk 7. THE UPPER LIMB Evolution of the Forelimb The Origin of Tetrapod LimbsThe Mammalian ForelimbHominoid Adaptations The Pectoral GirdleThe ElbowHands Knuckle-WalkingHuman Hands Adaptations for ManipulationEvolution of the ThumbFossil Tool-Makers?8. THE LOWER LIMB The Pelvis Adaptations of the Hip Joint for BipedalismThe Thigh The Knee Adaptations of the Knee for BipedalismThe Leg The Ankle and Foot The Bones of the FootThe ToesEvolutionary Trends in Ankle and Foot MusculatureThe Longitudinal Arch of the Foot Conversion Mechanism of the FootSupport for the ArchFunction of the Longitudinal ArchFunctional Variation in the Design of the Arch9. THE HUMAN STRATEGY: BIPEDALISM The Transition to Bipedalism The Pelvis and HipThe KneeThe FootThe Australopithecine BodyAfter the AustralopithecinesThe Adaptive Significance of Bipedalism Historical Speculations Concerning the Origin of BipedalismThe Problem with Cultural ModelsReconstructing the TransitionPART III. THE NERVOUS SYSTEM 10. ORGANIZATION OF THE BRAIN Initial Development of Nervous System General Anatomy of the Brain The BrainstemThe ForebrainDiencephalonCerebrumFunctional Organization of the Brain Specific and Nonspecific Projections ConsciousnessFunctional Localization Somatotopic Organization Phylogenetic Layering The Motor SystemDecussation Functional Lateralization Language and LateralizationThe Evolution of Language and LateralizationLateralization in PrimatesEvidence of Language in Nonhuman PrimatesFossil Evidence for LanguageIntegration with Other Systems The Neuroendocrine SystemThe Autonomic NervesThe Neuroendocrine AxisNeuroendocrine Integration: The Stress ResponseIntegration with the Immune SystemIntegration with Consciousness: The Limbic SystemEmotionsThe Reward SystemMemory11. THE HUMAN STRATEGY: BRAIN SIZE Comparing Brains The Relation of Brain and Body SizeBrain Size and FunctionThe Rate of Hominin Brain EvolutionSelecting for Brain Size The Social ModelDietary ModelsMetabolic NeedsEnvironmental ModelsOvercoming Constraints Selecting for Reorganization and New Abilities Developmental PossibilitiesQualitative Differences in Function12. THE SPECIAL SENSES Olfaction Central PathwaysThe Evolution of SmellThe Vomeronasal OrganTaste Vision Frontally Directed VisionPhotoreceptors and Color VisionEvolution of Vision in the BrainEquilibrium Hearing The Outer and Middle EarsThe Evolution of the EarPART IV. SYSTEMS OF HOMEOSTASIS 13. SKIN The Anatomy of Skin The EpidermisThe DermisThe HypodermisDifferences among VertebratesGetting a Grip: Fingerprints and Nails Friction Pads and FingerprintsNailsHair Hair ReductionGlands of the Skin Apocrine GlandsEccrine GlandsSweat and Hair Reduction as a Human Strategy for Thermoregulation A Problem of Fat Fat as InsulationFat Is an Adaptation for the BrainExplaining Human Skin Pigmentation Melanin and PhotoprotectionThe Vitamin D HypothesisOther Hypotheses of Human PigmentationMore PigmentsHair and Eye ColorMelanin in Other TissuesGenetics of Skin Pigmentation14. DIGESTION AND DIET A Natural Diet The Digestive System The Coelom and the PeritoneumTissue Structure of the Alimentary CanalOrgans of the Digestive TractThe Start of the CanalEsophagusStomachSmall IntestineAccessory GlandsColonReconstructing the Diet of Early Hominins The Evidence of Dental AnatomyThe Evidence of Dental MicrowearBone Composition and DietArchaeological Evidence of Meat ConsumptionAnd Other Evidence. . .Later Hominins A Backward Look from the Present Modern Hunter-Gatherer DietFeeding the BrainAnatomical Adaptations Frugivory, Carnivory, OmnivoryRecent Changes in Diet and Health 15. RESPIRATION Evolution of Vertebrate Breathing The Problem of Gas Exchange and TransportGillsLungs and Swim BladdersBreathing in Simple TetrapodsBreathing in MammalsMechanics of Human RespirationFunctional Specializations of the Human Respiratory Tract The Nasal PassagesThe PharynxThe LarynxThe Evolution of Speech Climatic Adaptations 16. CIRCULATION The Heart The Chambered HeartStructure and Function of the Human HeartEvolution of Vertebrate Circulation Circulation through GillsCirculation through LungsHuman Ontogeny Recapitulating PhylogenyThe Fetal Circulation PatternChanges at BirthCirculation and Thermoregulation Countercurrent Exchanges: Maintaining a Temperature DifferentialCooling the Body: Regulating Cutaneous Blood FlowCooling the Brain17. EXCRETION Evolution of the Vertebrate Kidney The Vertebrate NephronVertebrate StrategiesKidneys of Simple Vertebrates The Mammalian Kidney The Concentration of UrineHuman Water Balance 18. THE HUMAN STRATEGY: ENERGY FLOW, HOMEOSTASIS, AND ENDURANCE Limitations on Energy Processing Endurance Requires EnergyEnergy and Oxygen ConsumptionManaging HeatThe Significance of Body Size and Form Body Form and Climate AdaptationThe Human Strategy PART V. REPRODUCTION 19. REPRODUCTION The Origin of Sexual Reproduction Gametes and the Basis of Sexual SelectionDimorphism and Secondary Sexual CharacteristicsVertebrate Reproductive Strategies Mammalian StrategiesMenstruationThe PlacentaLabor and Delivery Labor: A Positive Feedback MechanismThe Anatomy of DeliveryThe Evolution of BirthLactation and the Breast The Composition of MilkBreasts and the Female Figure Breasts as Erotic AttractorsBreasts as AdvertisementsBreasts as Deceitful AdvertisementsThe Problem of Gender Recognition20. SEX AND HUMAN EVOLUTION Sexuality and Mating among the Apes Two Adaptationist ModelsThe Pair-Bond ModelThe Promiscuity ModelContrasting the ModelsSexual Selection in the Human Species Sexual Dimorphism in Body SizeEvidence for Sexual Selection of MenSexual Selection and Genital SizeSperm CompetitionEvidence for Sexual Selection among WomenSexual Selection and Contemporary Mate SelectionWomen: Choosing StatusMen: Choosing Reproductive PotentialSupport for the Pair-Bond ModelHuman Sexual Behavior The Problem of EstrusIs Ovulation Concealed?The Pleasure of SexThe Obscuring of Estrus: Support for the Promiscuity Model?Human Mating Systems Are FlexibleConclusions21. THE HUMAN STRATEGY: LIFE HISTORY The r and K Strategies TrendsHuman Life History Stages of Life HistoryFetal LifeInfancy and NursingJuvenile Life and ChildhoodSubadults and MaturityPostreproductive LifeLongevity and Evolution of the Modern Life SpanDental Maturation in Early HomininsForaging, Energy, and Society GlossaryBibliographyIndex